1. Field of the Invention.
The present invention relates to doctor blades, and, more particularly, to a doctor blade for leveling and/or metering a layer of liquid or viscous coating medium.
2. Description of the Related Art.
A doctor blade is used to level and/or meter coating medium onto a moving background. With direct application of the coating medium, a moving background is a material web, such as a paper or cardboard web. With indirect application, a moving background is the surface of a transfer element which transfers the coating medium onto the material web.
It is known for a doctor blade to be formed of materials such as high carbon spring steel, beryllium copper, stainless steel or fiberglass. A problem is that these materials have generally poor wear characteristics.
What is needed in the art is a doctor blade that has higher strength and better wear characteristics.
The present invention provides a doctor blade formed of a high strength composite material, such as carbon fiber. Also provided are various arrangements for positioning such a doctor blade relative to the moving background.
The invention comprises, in one form thereof, an apparatus for one of direct and indirect application of a coating medium onto a traveling fiber material web. At least one doctor element applies and/or meters the coating medium, and is formed of a carbon fiber material.
An advantage of the present invention is that, because of the higher strength and wear characteristics of the carbon fiber material, the doctor blade has a longer useful life.
Another advantage is that the doctor blade has better lubricity because of the carbon material.
Yet another advantage is that the position of the doctor blade relative to the moving background can be closely controlled.